We all get them but the question is how to get rid of them. You've got your opening, you even have your ending. You know what happens in between but you just can't get it on paper. Maybe it's your character(s), maybe the plot is weak, maybe you don't know what your story is about. It's possible you're bored and have moved on to another story. What do you do to avoid the blues and if you can't, how do you get out of it and push through to the end? My personal favorite is to go back to the point you're stuck at, take that out and re-write. But that doesn't always work. --- "does she have legs?"
Bury it in a drawer somewhere. Go for a long hike in a secluded area. Watch all three seasons of Sherlock in one day. Read a brilliantly written novel that makes you want to tear to shreds everything you've ever written and never touch a keyboard again. Then drag that story back out and write down all the questions concerning everything that's bugging you with it. Ask the famous "what if" question. Ask whether or not the story is even worth finishing. If it is, then figure out why and use that as motivation to figure out what needs to be done to the story. And then fix it. Easier said than done, I know. In all honesty, this method doesn't always work either.
I think the most important thing is choosing the right idea, from the pool of ideas we all have, to make into a story. Some ideas stop fascinating us at 'what if?' Others might progress towards a general idea of what we want to say, others, still might make it to a few chapters. But only the idea you can see yourself not getting bored of despite sweating blood, sweat and tears to write it, for several years mind, (2-4 on average), are those that will actually turn into a novel. Only you can decide if the story you are writing is the story you should be writing. If after some soul searching you decide this is definitely the story you want to be writing (you are passionate about it, about the theme, message, characters, the story) you need to commit to it. In my experience, novels never 'write themselves'. Novels are diamonds in the rough, to be kind. Save for those few crystal clear scenes you might have in your head, every plot idea you'll have will be lame, and you'll have to reach deep and deeper inside, desperately look around, try to figure out how to make the lame first thought into something sophisticated and capable of both communicating the soul of you story to the reader as well as make you proud of your own work. It is very hard writing a good novel. It's the essence of what we do though. Don't leave it, don't give up at the first hurdle. Good luck!
